Ask Dr. K: Vaccine reduces shingles risk in adults over 60

DEAR DOCTOR K: I have never had chickenpox. Do I still need to get a shingles vaccine?

DEAR READER: Not everyone knows the connection between chickenpox (a childhood disease) and shingles (a condition that usually hits adults). So let’s begin with that.

Chickenpox and shingles are both caused by the same virus: varicella-zoster virus (VZV). Once you have had chickenpox, VZV remains in your body’s nerve tissues for the rest of your life, alive but inactive. But it can be reactivated later in life, causing shingles.

Not long ago, nearly every kid got chickenpox. Today, fewer kids get it, thanks to the varicella vaccine (Varivax), which was approved in 1995. Shingles is also on the decline, thanks to the Zostavax vaccine, which was approved for older adults in 2006.

After you are first infected with the virus, it takes up permanent residence in your nerves. Specifically, it finds its way to the knots of nerve cells on each side of your spinal cord, called the dorsal root ganglia. The nerve fibers that sense pain in your skin lead to these ganglia.

When the virus reactivates (or “reawakens”) in the dorsal root ganglia, it travels down the nerves that lead to the skin. This causes a burning or tingling sensation or a shooting pain. Your skin may be extremely sensitive — so much so that you cannot stand clothing touching or rubbing the area.

After a few days, the virus reaches the skin. Painful, itchy blisters may cluster in patches, or form a continuous line that roughly follows the path of the infected nerve.

About 10 percent of adults who get shingles experience post-herpetic neuralgia. This is long-term pain in the area of skin where blisters occurred, even after the rash has healed completely. This condition may last for months or even years.

So, to your question: Since you never had chickenpox, should you get the shingles vaccine? Yes. Not everyone who becomes infected with VZV gets chickenpox. You may have been infected, and thus may be at risk for shingles.

The vaccine reduces your risk of developing shingles by about 50 percent if you are 60 or older. (There is some controversy as to whether the vaccine is as effective in people aged 50-59.) The vaccine also reduces the intensity and duration of symptoms in people who do get shingles despite having received the vaccine.

Dr. Anthony Komaroff is a physician and professor at Harvard Medical School.